The present invention generally relates to machining equipment, and more particularly to a tool holder assembly capable of providing controlled modulation (e.g., forced displacement) of a cutting tool during a machining process, such as for the purpose of producing chips having nanocrystalline microstructures and desirable sizes and shapes.
Developments in cutting tool technology have been generally directed to the use of advanced materials and coatings, unique geometries, and combinations thereof to improve tool life, reduce cutting forces, and reduce machining effluent streams. Geometric chip breaker features on cutting tools have been introduced specifically to promote chip breakage, though generally without the capability of creating separation between the tool and workpiece interface or controlling the size of the machine chips. Chip breakage during drilling has also been achieved through modulation, in which the drill bit is axially displaced in a cyclical manner. In addition to achieving chip breakage, modulation-assisted drilling has also been demonstrated to improve drilling performance and reduce the need for cutting fluids. For example, modulation-assisted deep hole drilling (hole aspect ratios with length to diameter (L/D) ratios of up to twenty) with minimal lubrication has been demonstrated. Such findings have been expanded to demonstrate that modulation can improve the lubrication effectiveness on metal cuttings. Such areas of research can be extended to enhance machining performance and reduce machining effluents through process control and innovation with positive impact on energy consumption and ecology.
Aside from the above, current state-of-the art machining practices do not consider modulation as a desirable parameter. The aforementioned research has generally been carried out using specialized equipment specifically designed and assembled for applying modulation in machining processes, and economic barriers exist with respect to capital cost of the technology in machine design or industry application. As such, general machining process design emphasizes the elimination or reduction of vibrations, which are commonly associated with instabilities that are detrimental to the performance of the machining process.